With increase in frequency of a.c. supply, the impedance of an $\mathrm{L}-\mathrm{C}$-R series circuit
With increase in frequency of a.c. supply, the impedance of an $\mathrm{L}-\mathrm{C}$-R series circuit
remains constant.
increases.
decreases.
decreases at first, becomes minimum and then increases.
Solution
We know
$\mathrm{X}_{\mathrm{L}}=\mathrm{L} \omega$ and $\mathrm{X}_{\mathrm{C}}=\frac{1}{\mathrm{C} \omega}$
$\Rightarrow$ When the frequency increases, $X_{\mathrm{L}}^{\prime}$ increases and $X_c$ decreases.
$\therefore \quad$ The impédance of an LCR series circuit decreases at first, becomes minimum and then increases.